A thick dust storm blows across Mars in this image from Mars orbit. Thin clouds are also visible in the image at top right and bottom center. Mars is one of several worlds in the solar system that produces weather. [NASA/JPL]

It's the number one topic for idle chit-chat. It has a big effect on our lives. And it's not limited to our own planet -- or to planets at all.

This catch-all topic is the weather -- changes in local conditions caused by large-scale changes in the atmosphere. At this time of year, much of the United States can expect the weather to be hot and dry, although some regions will see thunderstorms and even early-season tropical storms.

Other planets have weather, too. On Mars, for example, it's always cold and dry. But the difference between a cold winter night and a warm summer afternoon can be up to a couple of hundred degrees. And individual weather systems can bring strong winds, blowing dust, and even snow.

The giant outer planets have weather in their turbulent atmospheres, too. Giant thunderstorms pop up on Jupiter and Saturn, for example, with powerful downdrafts and big blasts of lightning.

Stars can have weather, too. The Sun, for example, produces magnetic storms known as sunspots. These storms are thousands of degrees cooler than the surrounding gas. And they're involved in giant eruptions of energy and charged particles.

These outbursts, along with the steady flow of the solar wind, are responsible for space weather. As particles hit a planet's magnetic field, they squeeze and heat the atmosphere, and create the shimmering curtains of light known as aurorae -- one more subject to bring up when you talk about the weather.